The N.C. Senate gave tentative approval Tuesday to a bill that makes Duke Energy close its 33 coal ash ponds in the state within 15 years, but it blocked a vote on shifting costs away from consumers.

The measure passed 45-0 on its second reading after sailing through committees last week. A third Senate vote, expected Wednesday, is required. A companion bill in the N.C. House is still in committee.

The measure sets deadlines of 2019, 2024 and 2029 for Duke to close its ponds, based on three risk levels. State environmental officials and a new, appointed Coal Ash Management Commission would assign those priorities.

Senators scrambled Tuesday to add more power plants to the four the bill targets for the quickest cleanups. They also debated who will pay for cleanup costs Duke has estimated at up to $10 billion.

Sen. Mike Woodard, D-Durham, tried to add an amendment placing the costs of closing the ash ponds on Duke.

The legislation holds utilities accountable only for cleaning up spills like the one on the Dan River. Duke has said it would seek Utilities Commission approval to pass other costs to its customers.

“It is Duke’s obligation to pay this and share these costs with its shareholders,” Woodard said, citing the company’s $2.7 billion in profit last year and recent rate hikes. “We have an obligation to consumers.”

Sen. Tom Apodaca, R-Hendersonville, the Rules Committee chairman steering the bill through the Senate, avoided a vote on costs by substituting his own amendment. His changes, dealing with hazard rankings and extending the monitoring of water around ponds from 20 years to 30 years, passed.

Some analysts, including the green-energy advocacy Institute for Energy Economics and Financial Analysis, have said Duke could bear those costs without rate hikes.

The complexities of Duke’s finances, Apodaca said, “is exactly why I don’t think we need this amendment. That is what the Utilities Commission is charged with, to take all evidence, all financial ramifications and make an informed decision.”

Protecting drinking water

The bill gives special treatment to four of Duke’s 14 coal plants in the state, including Riverbend on Mountain Island Lake, Charlotte’s drinking water supply, and Dan River, scene of a Feb. 2 ash spill. Ponds at those plants, deemed to be especially risky, have to close by 2019.

The Senate voted down a series of attempts to add four more plants to the quick-action list.

“The reason these amendments are coming is that we don’t know why these four plants were chosen other than that they were in the governor’s bill,” said Sen. Jeff Jackson, a newly appointed Charlotte Democrat. “That’s not a good answer.”

Jackson’s amendment would have added the Marshall power plant on Lake Norman to the high-risk group. “If it goes, you’ve got contaminated drinking water for 1 million people,” he said.

The four plants identified in the bill were those where Duke has said it will remove ash or close ponds. Three of the four are retired, and all are near water supplies. Gov. Pat McCrory’s bill, which became the foundation of the Senate bill, placed top priorities on the same group.

Senators tried unsuccessfully Tuesday to add to that list: Duke’s Cape Fear plant in Moncure, where millions of gallons of wastewater were released this year; the Buck plant in Rowan County, where residents suspect contamination is making them sick; and the Cliffside plant in Rutherford and Cleveland counties.

“What we’re doing, folks, is nit-picking a bill to death that means nothing,” said Sen. Jerry Tillman, a Randolph County Republican. “The (ash) commission will decide priorities.”

The Senate passed an amendment by Sen. Fletcher Hartsell, R-Cabarrus, intended to expand use of ash in road-building and other uses. Duke now sells about one-quarter of its ash to concrete makers and 40 percent as structural fill that prepares building sites.

A Democratic amendment that would have required liners in low-risk ponds where ash is capped in place that are found to leak was withdrawn. The amendment would also have strengthened a groundwater contamination standard.

Debate over priorities

Duke is still concerned about the 15-year timeline the Senate bill sets, said spokesman Jeff Brooks.

“We want to understand better how those sites will be prioritized,” he said. “The uncertainty around those priorities prevents us from knowing what our options for closure will be” and whether the deadlines are workable.

Environmental groups say the bill guarantees ash removal at only some of Duke’s power plants. They say it lacks standards for setting cleanup priorities and for deciding how the ponds will be closed.

“Without specific guidelines for prioritizing sites, it’s likely that much of the ash will remain in place, where it’s illegally polluting groundwater at all 14 facilities across North Carolina,” Peter Harrison, staff attorney for Waterkeeper Alliance, said in a statement.

The alliance says its testing of 14 wells near the Buck plant found hexavalent chromium, a carcinogen. Duke disputes the test results.

“This has been around since the 1930s, and the fact is, none of us has done anything to correct that,” Apodaca told his colleagues. “But we have that opportunity today.”

This article was modified on June 25, 2014, to correct that a Democratic amendment on capped ash ponds and a groundwater standard was withdrawn.